阿米洛利对豚鼠心肌细胞钾电流及钙电流的作用

目的研究阿米洛利（amiloride）对豚鼠心肌细胞钾电流及钙电流的作用。方法采用全细胞膜片钳技术记录豚鼠心室肌细胞钾通道及钙通道电流。结果阿米洛利在10~100 μmol·L^-1抑制L型及T型钙电流,不改变钙电流I-V曲线的形状，仅抑制这两型电流的幅度。当累积浓度达100 μmol·L^-1时，阿米洛利轻微抑制快激活延迟整流钾电流(I_Kr)，对慢激活延迟整流钾电流(I_Ks)无影响。阿米洛利在1~100 μmol·L^-1浓度依赖性地抑制内向整流钾电流(I_K1)。结论阿米洛利抑制电压依赖性的钾、钙电流，为其抗心律失常作用提供了离子基础。

Effects of amiloride on potassium and calcium currents in guinea pig ventricular myocytes

AIM: To elucidate the possible mechanisms underlying antiarrhythmia of the non-selective Na+/H+ exchanger inhibitor--amiloride. METHODS: Single ventricular cells were isolated using a double-enzyme method. Effects of amiloride on voltage-dependent potassium and calcium currents in isolated guinea pig ventricular myocyte were recorded by using whole-cell patch clamp techniques. RESULTS: Exposure to amiloride (10 -100 micromol x L(-1)), the L-type and T-type calcium currents were depressed. Amiloride resulted in a concentration-dependent inhibition of peak (Ca,L), But amiloride did not change the shape of their I - V curves. It only decreased the amplitudes of the currents of the two types. When myocytes were incubated with 100 micromol x L(-1) amiloride, I(Kr) was slightly depressed and I(Ks) did not change. Amiloride (1 - 100 micromol x L(-10) depressed I(K1) in a concentration-dependent manner. CONCLUSION: Amiloride depressed potassium and calcium currents, which may give support to its uses in some diseases of the cardiovascular system.